Chemical Properties
Antimony pentasulfide is an orange to dark red powder. It is doubtful whether stoichiometric Sb2S5 exists, because the preparations contain free sulfur and have variable composition. Antimony pentasulfide is insoluble in water but soluble in alkalies and alkali-metal carbonates.
Physical properties
Orange-yellow or reddish amorphous powder; density 4.12 g/cm
3; decomposes at 75°C; insoluble in water and alcohol; soluble in hydrochloric acid, caustic alkalies and ammonium hydrosulfide.
Uses
As pigment; vulcanizing and coloring rubber; manufacture of matches and fireworks.
Preparation
The compound is made commercially by converting antimony trisulfide to tetrathioantimonate by boiling with sulfur in caustic soda solution:
4 Sb
2S
3 + 8 S +18 NaOH → 5 Na
3SbS
4 + 3 NaSbO
3 + 9 H
2O
The sparingly soluble sodium antimonate is filtered out of the solution. The yellow-orange antimony pentasulfide precipitates out on treatment with hydrochloric acid.
2 Na
3SbS
4 + 6 HCl → Sb
2S
5 + 6 NaCl + 3 H
2S
It may also be prepared by the reaction of antimony pentachloride in HCl with hydrogen sulfide and removing any free sulfur by extraction with carbon disulfide:
2 SbCl
5 + 5 H
2S → Sb
2S
5 + 10 HCl.
Definition
ChEBI: Antimony pentasulfide is a sulfide and a p-block molecular entity.
Hazard
Flammable, dangerous fire risk near oxi-
dizing materials.
Safety Profile
Moderately toxic by
intraperitoneal route. See also ANTIMONY
COMPOUNDS and SULFIDES.
Flammable when exposed to heat or by
chemical reaction with powerful oxidtzers.
Use water to fight fire. Moderately explosive
when shocked or by spontaneous chemical
reaction in contact with powerful oxidtzers.
When heated to decomposition or on
contact with acid or acid fumes it emits
highly toxic fumes of oxides of sulfur and
antimony. Incompatible with water or steam
to produce toxic and flammable vapors and
with oxidizers, e.g., Ag(ClO3)2, HClO3,
ClO2, Mg(ClO3)2, TlO,Zn(ClO3)2.
